An LCD panel source driver converts a group of externally inputted digital signals to an analog signal at a corresponding level, amplifies the converted analog signal by a prescribed amplification gain, and then provides the amplified analog signal as a panel source signal for driving a display panel.
FIG. 1 is a diagram of an AMP output stage circuit for an LCD panel source driver according to a related art. Referring to FIG. 1, if an output of PAMP or NAMP in an AMP output stage circuit becomes greater or smaller than HVDD, it may cause a problem that a diode 102/104 within PMOS/NMOS loaded in an output circuit within an amplifier can be turned on. Particularly, this problem may be caused if the circuit is reactivated for a whole charge sharing interval 200, as shown in FIG. 2, after completion of the charge sharing.
As mentioned in the foregoing description, in the AMP output stage circuit according to the related art, since a source voltage of the PMOS/NMOS is higher than a body voltage, a threshold voltage Vth attributed to a body effect is raised. In this case, a body bias control circuit is added, which increases a die area. Moreover, if an attempt is made to protect the output of the AMP using a protective diode only, the size of the diode needs to increase. Therefore, a corresponding die area must be increased as well.